Reza Naima has been working on an Arduino G-Code Interpreter. There have been a few other projects like the grbl projects and the rerap type machines have some g-code history to them. Most of the project is being documented over at the rStep Google Group.

It is nice to see more and more open source G-Code interpreters for micro controllers out there. In some projects this can free up the PC or at least reduce the need for expensive and or complicated CAM controllers like Mach3. A quick look at the firmware shows it handles a decent sub set of G-Code commands including arcs.